How to use de-icer
Updated: 23 October 2026
You are outside a frozen car with the kettle in your head and a small clear patch where the wipers sit. How to use de-icer, on a UK morning, is an order of work: snow off, spray from the top, wait, then every window, mirror, lamp and plate before the car moves. A porthole in front of the driver is not a clear screen. This page does not rank bottles. Prices and formats are on the [de-icer comparison](/hub/diy-supplies/de-icer). Peter F., DIY & tools editor, used the Highway Code, the RAC de-ice guide and these listings on 21 October 2026. A qualifying purchase can earn a commission at no extra cost to you.
You are outside a frozen car with the kettle in your head and a small clear patch where the wipers sit.
You are outside a frozen car with the kettle in your head and a small clear patch where the wipers sit. How to use de-icer, on a UK morning, is an order of work: snow off, spray from the top, wait, then every window, mirror, lamp and plate before the car moves. A porthole in front of the driver is not a clear screen. This page does not rank bottles. Prices and formats are on the de-icer comparison. Peter F., DIY & tools editor, used the Highway Code, the RAC de-ice guide and these listings on 21 October 2026. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Format | Job | Pack | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Autoglym Autoglym De-Icer 500 ml | Trigger | Morning melt | 500 ml | 9.4 | about £7.00 | View offer |
| Alternative |  Prestone Prestone Rapid de-icer 6 pack | Spray multipack | Morning melt | 6 pack, fill not printed | 9.4 | about £15.49 | View offer |
| Best value |  CarPlan CarPlan Blue Star trigger 500 ml × 2 | Trigger | Morning melt | 2 × 500 ml | 8.8 | about £5.12 | View offer |
On this page
What you have to clear
Highway Code rule 229 says you must clear all windows, lights, plates and mirrors, demist the glass, and remove snow that could fall into another road user’s path. Regulation 30 says the glass must not obscure the driver’s view. nidirect cites regulation 35 for the same duty, not a separate Northern Ireland fine. Annex 5 lists a maximum of £1,000 and 3 points for failing to have a full view ahead. That is a maximum, not a ticket you can predict. Ask the Police says roof snow is not its own offence. Clear it anyway under rule 229. A named bottle is on the best de-icer page.
The morning sequence
Brush loose snow off the roof, bonnet, lamps and glass before you spray. Dry snow only gets wet. Autoglym says remove heavy snow, spray, then use the wipers or a squeegee. Prestone says score thick ice. The RAC’s shape for a full clear is about ten minutes, a rule of thumb, not a timer. Spray from the top, wait, then use a plastic scraper. Credit cards and metal blades mark the glass. Free the wiper blades before you switch them on. Keep one bottle indoors, and stay with the car if the engine is running to demist. That is Aviva’s line. A night film was yesterday’s job.
Thick ice, wipers and the washer bottle
On thick ice the spray melts a little, dilutes, and stops. Score the sheet, wait, then scrape. Turn automatic wipers off before a blade is glued down. Interior mist is the heater and demister, started cooler. The washer bottle wants winter screenwash, not de-icer. Do not pour boiling water over the bonnet. A pump is easier on cold hands and a can is easier to aim at a lock, which is the trigger or aerosol page.
What not to pour on the glass
Do not pour boiling water on the windscreen. The RAC says the thermal shock can crack the glass. Lukewarm water is only the fallback when you have no spray, and Aviva is harder where the screen is chipped. Do not use a vinegar or salty-water recipe. Do not pierce an aerosol or store it above 50°C. That is a storage cap, not the melt rating. If a child or a pet swallows the fluid, call NHS 111 or a vet and keep the bottle. A cracked screen is a glass fitter’s job. A burnt wiper motor is a workshop.
Common questions
What order do I de-ice the car?
Brush loose snow off the roof, lamps and glass first. Spray from the top, wait, then use a plastic scraper or the wipers once the blades are free. Clear the side windows, mirrors, lamps and plate before you move. The RAC’s shape for that full clear is about ten minutes. A second coat belongs on ice you have scored, not on a solid sheet you hope will melt in one go.
Do I have to clear the side windows and mirrors as well?
Yes. Rule 229 says all windows, mirrors, lights and plates, and glass that does not obscure the driver’s view under Construction and Use regulation 30. A hole in front of the driver leaves the rest of the car blind at junctions. nidirect cites regulation 35 for the same duty. Roof snow is not its own offence in the Ask the Police note, and you still clear snow that could fall into another driver’s path.
Can I pour boiling water on the screen?
No. The RAC says the thermal shock can crack the glass. Hot water is the same risk. Lukewarm water is only the RAC’s fallback when you have no de-icer at all, and a chipped screen is a reason to be more cautious, which is Aviva’s line. If the engine is running to demist, stay with the car. Do not leave it unattended on the street.
What if the wipers are frozen to the glass?
Switch automatic wipers off. Free the blades with spray along the rubber, or lift them only when the ice releases, and do not force a sweep. A motor that burns out is a workshop visit, not another bottle. Credit cards and metal blades mark the glass, so use a plastic scraper on the slush the spray has made. The blades go back down before you drive.
Where should the bottle live overnight?
Indoors, not locked in the frozen car. You need it before you can open the door. A second bottle in the house is the pattern in the trigger reviews, and it matches the Met Office idea of keeping winter kit where you can reach it. An aerosol should not be pierced or stored above 50°C. That is a storage limit, separate from the melt temperature on the label.
Is screenwash part of this job?
It is the next check, in its own bottle. Winter screenwash belongs in the washer reservoir so the jets work once you are moving. De-icer does not go in that reservoir, in the coolant, or on the inside of the glass. Interior mist is the heater and the demister, started cooler, not more spray on the outside. Frozen jets are not a reason to pour boiling water over the bonnet.
When does a cracked screen stop being a DIY job?
As soon as the glass cracks, including after a thermal shock. A glass fitter takes a cracked screen. A workshop takes a failed wiper motor. If someone has swallowed the fluid, NHS 111 or a vet is the call, with the bottle kept for the label. Brown liquid that has separated goes back to the seller. None of those are fixed by a second coat on the windscreen.
Related pages
Sources
Public UK sources and the amazon.co.uk listings compared on this page. Updated 22 October 2026.
- Highway Code rules 226 to 237 (retrieved 22 October 2026)
- Highway Code Annex 5, penalties (retrieved 22 October 2026)
- Construction and Use Regulations 1986, regulation 30 (retrieved 22 October 2026)
- RAC: how to de-ice your car (retrieved 22 October 2026)
- Met Office winter resources (retrieved 22 October 2026)
- Met Office: winter (retrieved 22 October 2026)
- Autoglym De-Icer DI500 (retrieved 22 October 2026)
- MyMotorWorld: CarPlan Demon Ice (retrieved 22 October 2026)